五唇兰未受精胚珠离体培养及雌配子体发育的研究

五唇兰(DoritispulcherrimaLindl.)的胚珠属于倒生型,具薄珠心,两层珠被。胚囊发育类型为双孢子葱型,授粉后约45d形成七细胞八核的成熟胚囊。五唇兰未受精胚珠在离体培养初期对外源激素的依赖性很小,在没有外源激素的培养基上,大孢子母细胞也能经过减数分裂发育为二核胚囊。在培养后期,外源激素对胚囊发育的影响很大。在培养基无外源激素或仅含生长素或细胞分裂素时,雌配子体的发生过程不能顺利完成;在改良VW培养基上添加0.5mg/LBA和0.1mg/LNAA时,形成成熟胚囊。     

五唇兰雌配子体发育和胚胎发生的研究

五唇兰的胚珠倒生型,具薄珠心,两层珠被。胚囊发育为双孢子葱型,成熟胚囊８核。从传粉到受精约５０ｄ,正常双受精。胚具５－６细胞的胚柄,种子成熟时胚柄及胚乳核消失,成熟种子只具单层细胞的种皮和一个未分化的珠珠形胚。     

刺五加大、小孢子发生和雌、雄配子体发育的观察

刺五加Eleutherococcus senticosus(Rupr．et Maxim．)Maxim．雄株的小孢子发生和雄配子体发育过 程正常,大孢子发生和雌配子体发育过程多不正常。雄花具5个花药,花药4室,药壁发育属双子叶型, 腺质绒毡层,绒毡层细胞多具2核。小孢子母细胞经减数分裂形成四面体形四分体,其胞质分裂为同时 型。成熟花粉为3细胞型。子房下位,5室;每室有上胚珠和下胚珠,上胚珠退化,下胚珠倒生、具单珠 被、厚珠心;大孢子母细胞经减数分裂形成线形或“T”形四分体,偶尔有2个并列或串联的四分体或在 四分体之上又出现孢原细胞。其功能大孢子位置不确定。雌配子体发育中异常现象较多。开花时,雌 配子体主要为反足细胞退化后的四细胞胚囊。刺五加雌株的小孢子母细胞不能进行减数分裂或减数分 裂不正常,不能形成四分体。开花时,药室空瘪,无花粉形成。其大孢子发生和雌配子体发育过程正常, 大孢子母细胞减数分裂形成线形或“T”形四分体,合点端大孢子为功能大孢子,胚囊发育属蓼型。开花 时,雌配子体主要为七细胞八核或七细胞七核胚囊,其卵器尚未发育成熟。刺五加两性株的小孢子发生 过程无异常,但雄配子体发育过程有部分异常;开花时,药室内有或多或少的空花粉,且花粉粒大小悬 殊,大的直径达35μm,小的仅15～18 μm。两性株的雌蕊发育大部分正常,也有一些异常胚囊形成。开 花时,雌配子体主要是七细胞八核胚囊、七细胞七核胚囊和反足细胞退化后的四细胞胚囊,其卵器也未发育成熟。     

小叶兜兰的果实生长和雌配子体发育

为了解濒危兰科植物小叶兜兰(Paphiopedilum barbigerum Tang et Wang)胚珠和雌配子体的发育过程,采用常规石蜡切片技术对其果实的生长动态进行了研究。结果表明,授粉后60~75 d的蒴果内种子数量迅速增加,到授粉后120 d时种子充满整个蒴果。授粉后40 d的胎座上分化形成多数由1层表皮细胞包被1列细胞的胚珠原基;授粉后60 d时位于胎座指状结构末端处紧靠表皮细胞下方的孢原细胞分化为大孢子母细胞。之后,大孢子母细胞经过减数分裂和有丝分裂最终形成成熟胚囊;授粉后135 d胚囊发育成熟,附着在胎座上的种子个体分化明显。小叶兜兰胚囊的发育类型为双孢子葱型,胚珠为倒生胚珠,薄珠心,单珠被,成熟胚囊为8核。这为小叶兜兰的生殖生物学及繁殖体系的建立提供理论依据。     

延龄草(Trillium tschonoskii Maxim.)的胚胎学研究初报Ⅰ.——大孢子的发生及雌配子体的形成

本文描述延龄草(Trillium tschonoskii Maxim.)的大孢子发生,雌配子体的形成和雄配子体的形态。胚珠为倒生型,双珠被,厚珠心型。胎座为侧膜胎座向中轴胎座的过渡类型,胶囊发育为葱型的变异型。孢原细胞直接发生于幼胚珠的珠心表皮细胞之下,孢原细胞平周分裂,形成初生周缘细胞及初生造孢细胞。初生周缘细胞分裂先于初生造孢细胞,分裂结果与珠心表皮细胞共同形成了珠心组织。初生造孢细胞进一步发育,形成大孢子母细胞。大孢子母细胞经减数第一次分裂后,即出现壁,形成二分体。一般是珠孔端二分体细胞小于合点端二分体细胞,但偶尔也见到前者大于后者的情况。在二分体形成后珠孔端二分体细胞立即退化、或经减数第二次分裂后再退化(该次分裂多为斜向的)。合点端二分体细胞发育,经二核胚囊,四核胚囊,六核胚囊阶段至成熟胚囊。一般在珠孔端的周围淀粉粒丰富,并先于合点端的核进行分裂。珠孔端由二个助细胞,一个卵细胞构成卵器,助细胞具钩突,并具丝状器,两个极核。合点端常见多核仁的大核,成熟胚囊未见八核。成熟花粉粒为二细胞的,花药壁具变形绒毡层,花粉中充满淀粉粒。沼生目型胚乳。     

花叶开唇兰（兰科）大小孢子发生和雌雄配子体发育

花叶开唇兰的胚珠倒生,双珠被,薄珠心．雌配子体发育属蓼型,成熟胚囊７细胞．大小孢子发生过程中壁上都有胼胝质出现．小孢子四分体为四面体形,左右对称形,交叉形,Ｔ形,它们聚集成花粉小块．花粉散出时为２细胞型．药室壁４层,绒毡层底分泌型．     

兜兰胚胎学的研究

云南兜兰花药壁有五层细胞,绒毡层细胞具双核,属分泌型。小孢子母细胞减数分裂为同时型。四分体中四个小孢子呈四面体或左右对称式排列。成熟花粉为二细胞型。单粒分散的花粉包裹于黄色粘性物质中。生殖细胞最初形成的壁为胼胝质的,待游离到营养细胞质中时,具一层很薄的 PAS 正反应的壁,直到花药开裂时这层壁仍存在。成熟花粉无特化的萌发孔,只具薄壁区。胚珠为薄珠心,具一层珠被,胚囊发育为葱型,成熟胚囊为6—8核,胚发育过程中,具2—4细胞胚柄。胚乳具二核。种子成熟时胚柄及胚乳核都消失。成熟种子只具单层细胞的种皮和一个未分化的球形胚。     

车桑子大孢子发生与雌配子体发育

采用常规石蜡切片法,对车桑子大孢子的发生和雌配子体的发育进行观察,探讨车桑子自然结籽率低的原因和明确其胚胎发育特征。结果表明:(1)车桑子花柱有花柱道,子房3室,中轴胎座,横生胚珠,每心室两枚胚珠,双珠被,厚珠心,无承珠盘。(2)位于珠心表皮细胞下的孢原细胞经平周分裂产生造孢细胞,造孢细胞发育为大孢子母细胞,大孢子母细胞经减数分裂形成线性四分体,靠近珠孔端3个大孢子退化消失,靠合点端大孢子发育为功能大孢子,大孢子发生类型为单孢子发生型。(3)单核胚囊经3次有丝分裂形成7细胞8核的成熟胚囊,胚囊发育类型为蓼型。(4)花器官形态的变化和大孢子发育过程有一定联系,可根据雌花形态特征大致判断大孢子发育时期。研究认为,车桑子雌配子体发育过程中出现的胚囊不中空、游离核不进一步细胞化等异常现象,可能是导致车桑子自然结籽率低的原因之一。     

新疆阿魏的胚胎学研究

采用常规石蜡制片技术,对新疆阿魏不同发育时期的花和果实进行了显微切片观察.结果表明:新疆阿魏小孢子母细胞的减数分裂为同时型,小孢子四分体为四面体型和十字交叉型,成熟花粉粒为3-细胞型.雌蕊2心皮合生成2室,中轴胎座,每子房室内产生上、下2个胚珠原基,其中,下方的原基正常发育,而上方的原基停止发育并最终解体,因此,每室仅产生一枚发育正常的倒生胚珠,单珠被,薄珠心,胚囊发育为蓼型;珠被绒毡层和珠孔塞发生于大孢子四分体时期,并于四核胚囊时分化完全,八核胚囊时珠被绒毡层细胞径向延长;3个成熟的反足细胞具双核.胚乳发育为核型,细胞壁较厚,细胞排列紧密,可保护胚免受机械损伤及防止胚失水.胚乳细胞中含有大量PAS染色呈正反应的物质,一些胚乳细胞异常生长形成细胞体积大、核及核仁均较大的巨形细胞.胚胎发生为茄型,四细胞原胚为直线形,十六细胞原胚的顶部由2排各4个细胞组成.成熟种子具胚乳.     

四倍体双穗雀稗兼性无孢子生殖的研究

研究了四倍体双穗雀稗(Paspalum distichum L)无孢子生殖胚囊、胚胎发育以及假受精特点。当其大孢子母细胞发育至四分体阶段时,大多数情况下会发生四分体退化,同时有多个特化珠心细胞发育为1—3个无孢子生殖胚囊的现象。成熟无孢子生殖胚囊一般3核,包括1个卵细胞和2个极核。卵细胞在抽穗前就能自发分裂形成原胚团,而极核则在抽穗和传粉后参与假受精形成胚乳。当胚珠内存在多个无孢子生殖胚囊时,只是靠近珠孔端的1个无孢子生殖胚囊内的极核与精核结合,而其它的并不参与。种子成熟后出现很低频率的二胚苗。此外,还能观察到少量的有性生殖胚囊的发育以及有性生殖胚囊和无孢子生殖胚囊在同一胚珠中的发育现象,因此判断该类群为兼性无孢子生殖体。     

Guidance in vitro of the pollen tube to the naked embryo sac of torenia fournieri

The precise guidance of the pollen tube to the embryo sac is critical to the successful sexual reproduction of flowering plants. We demonstrate here the guidance of the pollen tube to the embryo sac in vitro by using the naked embryo sac of Torenia fournieri, which protrudes from the micropyle of the ovule. We developed a medium for culture of both the ovule and the pollen tube of T. fournieri and cocultivated them in a thin layer of solid medium. Although pollen tubes that had germinated in vitro passed naked embryo sacs, some pollen tubes that grew semi-in vitro through a cut style arrived precisely at the site of entry into the embryo sac, namely, the filiform apparatus of the synergids. When pollen tubes were unable to enter the embryo sac, they continuously grew toward the same filiform apparatus, forming narrow coils. Pollen tubes selectively arrived at complete, unfertilized embryo sacs but did not arrive at those of heat-treated ovules or those with disrupted synergids. These results convincingly demonstrate that pollen tubes are specifically attracted to the region of the filiform apparatus of living synergids in vitro.     

Micropropagation of sweet orange, Citrus sinensis Osbeck. for the development of nucellar seedlings

Protocol for micropropagation of elite plants of sweet orange (Citrus sinensis) through nucellar embryo culture has been standardized. Three to four nucellar embryos and a zygotic embryo could be excised from a single mature seed and successfully generated as healthy plants in basal MS medium. MS medium supplemented with NAA (1 mg/L) or 2, 4.D (1 mg/L) promoted callus development in both nucellar and zygotic embryos. GA3 (1 mg/L) enriched medium induced plantlets initiation but their growth was very poor. No significant differences were observed between initial growth patterns of nucellar and zygotic seedlings developing from the same ovule. Five to six shoots were obtained from collar region of both category of embryos in MS medium supplemented with BAP (1 mg/L) within 60 days of inoculation. The number of plantlets were almost doubled after their transfer in the same medium and culture for another 30 days. Higher doses of BAP resulted in initiation of callus directly from the embryos. The regenerated shoots (2-3 cm) could be rooted in MS medium supplemented with either only NAA (0.75 mg/L) or NAA (0.50 mg/L) and IBA (2.0 mg/L). A number of plantlets could be obtained from a nucellar embryo grown shoot within a limited time period.     

Cytological Observation on Megasporogenesis and Embryo Sac Development of Regenerated Ovule in Hyacinth

The morphogenesis of regenerated ovule and cytological changes of its megasporogenesis and embryo sac development were studied. Results showed as follows: 1. the differentiation of the regenerated ovule had followed a normal process in the order of inner integument , outer integument and then funiculus. But the form of the regenerated ovules in vitro was quite different from that of ovule in vivo. Most of the regenerated ovules were orthotropous and hemianatropous , only a few were anatropous which are the same with that in vivo. 2. the megasporogenesis and the embryo sac development also had normal cytological process ,and the Polygonum type-embryo sac consisted of one egg, two synergids , one central cell and three antipodals could be seen in mature regenerated ovule. These ex-perimental results make clear that the regenerated ovule differentiated directly from explant could accomplish the complex processes of megasporogenesis and embryo sac development. By this fact ,authors infer that once the differentiation of ovule primordium, the complex biochemical programs for the megasorogenesis and embryo sac development can be controlled by the ovule itself and need no more information from flower bud and /or plant.     

大叶杨配囊及胚珠的形成和发育

本文应用细胞化学方法研究了大叶杨胚珠、胚囊的形成和发育过程中核酸、蛋白质及不溶性多糖的分布和消长。大孢子母细胞、大孢子四分体及功能大孢子中含较少不溶性多糖,但却含丰富的RNA和蛋白质。功能大孢子经分裂发育成八核的蓼型胚囊。四核胚囊开始积累细胞质多糖,成熟胚囊中除反足细胞外充满淀粉粒。反足细胞形成后不久即退化。助细胞具多糖性质的丝状器,受精前两个助细胞退化。卵细胞核对Feulgen反应呈负反应。二极核受精前由胚囊中部移向卵器,与卵器接触后融合形成次生核。发育早期的胚珠为厚珠心,双珠被。晚期,内珠被退化,故成熟胚珠为单珠被。四核胚囊时期,珠孔端珠心组织退化,胚囊伸向珠孔形成胚囊喙。合点端珠心组织含丰富的蛋白质和核酸,这一性质与绒毡层性质相似,可能涉及胚囊的营养运输。胚囊的营养来源于子房和胎座细胞内贮存的淀粉粒。     

红花胚珠和雌配子体发育

用石蜡切片法研究了红花的大孢子发生和雌配子体发育过程,得到以下结果：（１）胚珠发育为薄珠心类型,倒生胚珠,具单珠被。（２）胚囊发育蓼型。（３）有珠被绒毛层,珠被绒毡层起始于大孢子母细胞时期,单核胚囊阶段高度发育,受精后从合点端逐渐退化。珠孔塞细胞呈毛状。     

Different patterns of callose wall formation during megasporogenesis in two species ofOenothera (Onagraceae)

The homozygousOenothera hookeri Torr. etGray shows the typical pattern ofOnagraceae with ± callose on the external walls of megaspore mother cells and tetrads. Megasporogenesis is heteropolar, and the micropylar megaspore is the mother-cell of the 4-celled embryo sac. The complex-heterozygousOenothera biennis L. during megasporogenesis generally has callose not on the external cell walls but only on the transversal walls of the tetrad. In 95% of the ovules both the external chalazal and the micropylar megaspores develop to embryo sac mother-cells. Megasporogenesis is homopolar, and competition between two developing embryo sacs for nutrition in the ovule occurs. The embryo sac with the stronger genotype wins the race against the other one. Polarity phenomena during ontogeny of the female gametophyte are related to nutritional supply and hormonal induction from the ovule. The introduction of a developmental-physiological point of view into the discussion about the evolution of the embryo sac inOnagraceae is therefore justified.Stipendiatin der Alexander von Humboldt-Stiftung 1974/76.     

Functional Anatomy of the Ovule in Broad Bean (Vicia faba L.): Ultrastructural Seed Development and Nutrient Pathways

Ovules of broad bean (Vicia faba L.) were studied to discloseultrastructural features, which can facilitate nutrient transportto the embryo sac from 10 d after pollination (DAP) to the matureseed. Fertilization occurs during the first 24 h after pollination.The endosperm is a coenocyte, which is eventually consumed bythe embryo. By 10 DAP the inner integument is degraded and theouter integument adjoins the embryo sac boundary. The heart-shapedembryo approaches the embryo sac boundary at two sites, whichhere are named contact zones. Small integument cells in theneighbourhood of the first formed contact zones become separatedby prominent intercellular spaces. A heterogenous scatteringmaterial, probably representing secretion products accumulatesin these spaces. By 14-16 DAP the integument exudate disappears,and the suspensor degenerates. As the contact zones increasein size, wall ingrowths form a bridging network in the narrowspace between the embryo sac boundary and the extra-embryonicpart of the endosperm wall. The epidermal cells of the embryoseparate adjacent to these zones, and develop conspicuous wallingrowths. At 20 DAP vacuoles showing various stages in formationof protein bodies appear in the cells of the embryo.Copyright1994, 1999 Academic Press Vicia faba, broad beans, ovule, seed, nutrient transport     

Translocation of Uranin within the Living Ovules of Vanilla

In the ovules of Vanilla (Vanilla planifolia Andr.) before fertilization, outer integument surrounded the lower part of ovule. Uranin got into ovule through funiculus, forming, the first center of fluorescence at the chalaza zone of ovule. Then uranin was transported to micropyle end along inner integument, forming the second center of fluorescence at micropyle end of inner integument. Soon, fluorescence appeared in the egg apparatua. After fertilization, the outer integument ovule extended upward, forming micropyle ogerber with inner integument. After getting into ovule through funiculus, uranin spreads to- ward several directions: l. transported to outer integument at the entrance of micropyle; 2. transported downward to chalaza zone along outer integument at the side of funiculus; 3. extended from chalaza zone to the inside and to the outer integument at the side far from funiculus The ovules of Vanilla had no vascular bundles. On transporting in inner integument, however, the cells in inner layer next to the embryo sac appeared to be the major passage. In mature embryo sac, there was cuticle between inner integument and embryo sac at the half of micropyle end. But between embryo sac at the half of chalaza end and nucellus, cuticle was absent. Nutrient could get into embryo sac from chalaza end undoubtedly. As egg apparatus showed the fluorescence after formation of fluorescence center of inner integument at micropylar end, the possibility that nutrient got into embryo sac from micropyle could not be excluded.